Optimised approach for characterisation of cutting edge micro-geometry in drilling carbon fibre reinforced plastics(CFRP)

Machining carbon fibre reinforced plastic (CFRP) is an extremely abrasive process, requiring cutting materials of high hardness and sharp cutting edges at the same time. A detailed characterisation of the cutting edge micro-geometry is essential to optimise tools for CFRP machining. A powerful characterisation of tool micro-geometry, adapted for machining operations in CFRP, is presented in this study. Thereby, additional information regarding the contact conditions and tool geometry like rake or clearance angle is used to generate meaningful and reproducible parameters. A comprehensive quality criterion Q(crit) of the cutting edge is proposed, being correlated to the actual bore exit quality. Therefore, three meaningful micro-geometry parameters r (peak) , l (gamma) and r(sg) are considered. The characterisation method is applicable to diamond-coated and -uncoated carbide tools as well as solid diamond tools. The applicability of the approach is proved based on an experimental drilling study wherein the evaluated cutting edge quality is compared with the actual bore quality.